Electrical drill or hammer



J. F. McLEER ELECTRICAL DRILL 0R HAMMER original Filed oct. s, 1834 .July 5, 1938.

Patented July 5,19384 UNITED sTATEs PATENT OFFICE ausm ELECTRICAL nnrLL on Joseph F. Meneer, Brooklyn, NKY.' v Application October 3, 1934, Serial No. 746,699

usually portable member and a reciprocatory member which may carry, for example, a chuck for the connection of a drill or other tool and has for an object to provide an improved tool of this general type which may be operated from readily available electrical power.

The invention has been developed more particularly in connection with the design of drilling machines for drilling holes either a few feet or several hundred feetinto rock, and for the purposes of disclosure of the principles of the invention such anembodiment will be more particularly described.

In the accompanying drawing- Figure l is a view in side elevation of a rock drill embodying certain principles of the invention,

Fig. 2 is a vertical central sectional view of the drill,

'Fig. 3 is a transverse sectional view taken on the line 3-3 of Fig. 2,

Fig. 4 is a detail view showing the construction of the secondary element,

Fig. 5 is a view of another embodiment showing a hammer construction,

Fig. 6 is a view showing a motor and switch for controlling the three-phase current supplied 2H to the tool, and

Fig. 7 is a detail view indicating the winding of the primary of the electrical motor.

The drilling machine illustrated comprises a relatively stationary element 5 of a size and weight to be readily portable and a reciprocatory element 6 movable longitudinally therein. The stationary element comprises a casing having handles 'l supported by a tripod 8 to which the casing is adjustably connected. The reciprocatory element is arranged to be operated by an electric current, in the structure illustrated, a three phase current. 1

The electric motor for actuating the reciprocating member is similar in principle to an ordinary induction motor and comprises the primary elements lil and secondary elements I I, the primary and secondary elements, however, being straight instead of circular. that is to say they are in effect developments of the primary and secondary elements of a three phase motor.

-Both primary and secondary elements comprise laminated iron cores slotted to receive the primary windings I2 and the secondary closed cir-f cuit windings or squirrel cage grids I3.

The direction of movement of the reciprocat- Renewed April 16, 1938 ing element is reversed by a constantly actuated reversing switch controlling two of the three electric circuits oi the three phase circuit. This arrangement is best shown in Fig. 6 wherein a small motor i5 is constantly driven from two ci the three conductors i6, i1, I8 and a rotatable switch i5 is connected to said motor.

The switch is interposed in the three phase current supply circuit to alternate the connection to two of the conductors. As shown, brushes 2li and 2i connected to the current feed lines it and il engage continuous slip rings 23 and 2i. 'I'hese rings in turn are connected to split rings 25 and 28, the sections oi which are cross connected as indicated in the drawing to provide an alternation of connection between the mains i8 and il and the leads 21 and 28 of the reciprocating motor. The feed line i8 is directly connected to the motor, the current in this lead not being changed by the switch. By this arrangement the period of reciprocation of the reciproeating motor will be determined by the speed of the control motor and this may be adjusted in any known or suitable manner if adjustment is desired. In some instances it is convenient and. satisfactory to provide different armature windings in the motor in order to provide a limited number of desired speed changes o1' to provide a variable resistance in the motor circuit or a variable speed connection between the motor and switch.

Means is preferably provided for cushioning the upward or inoperative movement of the reciprocating member and returning the stored energy of such cushioning to the member to increase its downward or operative movement. As shown this is accomplished by providing the cylinder 3|! in which a piston 3i connected to the reciprocating member operates. A check valve 3241s provided in the top of the cylinder to admit air as indicated in Fig. 2, and a second valve is provided for insuring a predetermined compression in the cylinder. This valve may be a simple hand valve as indicated at 33 or it may be a valve arranged to close at a predetermined part of the stroke. Furthermore, a relief valve or safety valve may be provided in the cylinder to prevent too great a pressure in the cylinder.

The piston and cylinder also constitute means for providing compressed air and the axial rod ll of the reciprocating member is centrally drilled to provide an air conduit 35 through which compressed air may be led to the point of the drill for blowing away chips in operation. At the lower end of the casing a cushioning spring li is provided for cushioning the movement of the reciprocating member when the drilling machine is lifted or when for other reasons its downward movement is not suiiiciently stopped by the operative stroke. At the lower end of the reciprocating member a drill chuck l1 is provided. This chuck may be of any' suitable type such, for example, as a drill rotating chuck a' other desired type.

The reciprocating member is provided with guides 40 which operate in guideways Il in the side walls oi' the casing thereby cooperating with the rod 3l guided by a bearing l2 in the lower end of the casing and by the cylinder lli above.

It will be understood that while the drill is more commonly used in the vertical position shown in Fig. 2 it may also be used in horizontal position as indicated in dotted lines in Fig. 1 or in inverted or inclined position. When used in horizontal, inclined, or inverted position it may be desired to increase the pressure in the cylinder 30 and for this purpose the valve 33 may be partially or entirely closed. An adjustable relief valve M provides for varying the limit of compression.

AIn Fig. 5 is shown another embodiment of the invention better adapted for work where it is desired to use a hammer action. In this structure the reciprocating member is formed with a hammer head l5 and a drill or other suitable tool I6 is inserted in cooperative position. Any of the usual tools and any of the usual chucks or other connecting devices may be associated with the tool shown.

It will be understood that the foregoing particular description is illustrated merely and is not intended as defining the limits o! the inven tion. The construction obviously may be modied in accordance with the requirements of use, such as the weight of the drill parts and other features incident to the particular use.

I claim:-

1. A machine tool comprising a relatively stationary casing, a reciprocatory member guided for movement in said casing and means to reciprocate the latter comprising a poly-phase reciprocatory motor having a primary element carried by the casing and consisting of a slotted core member extending parallel to the line of movement oi the reciprocatory member positioned at one side .of

and with its slots facing said reciprocatory member and coils in said slots with their axes at right angles to the direction of movement of the reciprocating element, and a secondary element carried by the reciprocatory member comprising a slotted core member extending longitudinally of the reciprocatory member with its slots facing the primary element and a squirrel cage grid member positioned in said slots and means for periodically changing the current in the primary element to cause reciprocatory movement of the secondary element.

2. A machine tool comprising a relatively stationary casing, a reciprocatory member guided for movement in said casing and means to reciprocate the latter comprising a three phase reciprocatory motor having primary and secondary elements carried by the casing and reciprocatory member in cooperative relation, the primary elements beingpositioned on opposite sides of the reciprocatory member and having coils arranged progressivefy in three phase relation with .their axes at right angles to the direction oi.' movement oi the reciprocatory member and means for periodically changing the electrical connections to reverse the movement of the reciprocatory member.

3. A machine tool comprising a relatively stationary casing, a reclprocatory member guided for movement in said casing and means to reciprocate the latter comprising a three phase reciprocatory motor having primary and secondary elements carried by the casing and reciprocatory member in cooperative relation, said elements each comprising a slotted laminated core with coils positioned in the slots, the coils of 4the pri- 'mary and secondary elements lying in parallel 

